Gear cutting machine



M. M AAG. GEAR CUTTING MACHINE.

APPLICATION FILED DEC. 22, 1919.

Reissud uly 6, 1920 m; d 1 i .w

M. MAAG.

GEAR CUTTING MACHINE.

APPLICATION FILED 05c. 22. 1919.

Reissued-Jlily 6, 1920. 14,908.

TSHEETS-SHEEY 2.

M. MAAG.

GEAR CUTTING MACHINE.

APPLICATION,FILED DEC-22,1919.

Beissued July 6, 1920.

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M. MAAG.

GEAR CUTTING MACHINE. APPLICATION FILED 050.22, 1919.

Reissued J uly 6,

3110M: l'o'c llllllllllli m AN M. MAAG.

GEAR CUTTING MACHINE.

APPLICATION FILED nccizz, 1919.

Reissued-Ju1y 6, 1920. 14,908.

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M. MAAG. GEAR CUTTING MACHINE.

APPLICATION FILED DEC-22, I919.

Reissued July 6, 1920.

I 3144x214 f 01 M. MAAG. GEAR CUTTING MACHINE.

APPLICATION EILED DEC-22,1919.

Reissued July 6, 1920; 14,908.

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UNITED STATES PATENT OFFICE.

MAX MAAG, OF ZURICH, SWITZERLAND.

GEAR-CUTTING MACHINE.

Specification of Reissued Letters Patent. Reissued July 6, 1920,

Original No. 1,290,270, dated January 7,1919, Serial No. 115,469, filedAugust 17, 1916. Application for reissue filed December 22, 1919. SerialNo. 346,799.

To all whom it may concern Be it known that I, MAX MAAG, a citizen ofthe Republic ofswitzerland, residing at Zurich, Hardstrasse 219,Switzerland, have invented certain new and useful Improvements inGear-Cutting Machines; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and to lettersor figures of reference marked thereon, which form a part of thisspecification.

This invention relates to a machine for cutting spur-, screwand doublehelical spur-wheels, which works according to the rolling principle. Themultiple-tooth cutter or rack form of this machine receives areciprocating movement, while the blank is carrying out its wholerolling movement. 'hile the teeth are cut, the blank receivingsimultaneously a revolving movement, is moved so longin the longitudinaldirection of the cutter o rack form until one or more teeth arecompletely finished, whereupon said blank is moved back past the cutterto an amount corresponding to the number of teeth, which are completelyout, the cutter being inoperative during this backard movement of theblank. In addition to the movements' specified the blank is given anadditional backward and forward rolling movement to take up play.

The object of the invention is to provide a machine having thecharacteristics and ca pable of carrying out the operations as outlinedabove.

This invention will now be more particularliy described with referenceto the accompanyingdra wings, which illustrate a constructional exampleof the invention.

In these drawings Figure 1 is a side view, partly in section, of themachine,

Fig. 2 is a plan view of this machine, showing also certain parts insection,

Fig. 3 is a front elevation, partly in section, of the machine,

Fig. 41 is a section on the line A--B of Fig. 1., I

Fig. 5 is a rear elevation, partly in section, of the machine,

Fig. 6 is a section on the line C- D of Fig. 5.,

Fig. 7 is a vertical section through a box containing parts of a controlmechanism, Fl igz. 8 is a section on the line EF of FFig. 9 is a sectionon the line G- H of Fig. 10 is a plan view of a detail of said controlmechanism,

Fig. 11 is a side view of a further detail of this mechanism, 1

Figs. 12 and 13 are a side view and a development, respectively, of acontrol drum and levers acted upon by this drum,

Fig. 14. illustrates diagrammatically the sequence and the duration ofthe movements controlled by said drum, which are imparted to the tablecarrying the blank;

Figs. 15, 16, 17 and 18 illustrate details of the mechanism for drivingsaid control drum, the details shown in Figs. 15 and 16 being arrangedon one side of the drum and the details shown in Figs. 17 and 18 on theopposite side thereof,

Fig. 19 is a vertical section through a mechanism for moving the tablecarrying the blank and arranged within a table )ox,

Fig. 20 is a corresponding-horizontal sec tion and Fig. 21illlisfiafiflsffl detail ofthis mechanism. v

Fig. 22 is afront elevation, partly in section, of the toolorcutter-ram,

Fig. 23 is a section on the line I-K of v Fig. 22., i

Fig. 24 illustrates the supports for the movable cutter holder,

Fig. 25 is a' section on the line LM of Fig. 23,

ig. 26 is a detail of the mechanism for reciprocating the table carryingthe blank,

Fig. 27 is a detail of that part of this mechanism, which effects therevolving movement of said table,

Fig. 28 is a detail of the feed mechanism of the machine, 9 i i Fig. 29is a section on the line N() of Fig. 5.,

Fig. 30 is a section on the line PQ, of Fig. 6., and

Fig. 31 is a side view of the change gearings of the mechanism effectingthe movement of the table carrying the blank.

The machine forming the subject matter of the present inventioncomprises a number together with a disk 24, which is of differentmechanisms, which I shall now describe.

One of these mechanisms is the:

Mechanism for moving the blank.

The standard 1 of the machine (Figs. 1, 3, 4) has a slide 2 for thelongitudinal slide 3 (Figs. 1, 2). .The latter carries aguide for thecross slide 4. The lower slide 3 ma be adjusted by means of a hand-wheel5 (Figs. 1, 2, 3)., spindle 6, bevel-gearing 7 (Fig. 3) and a screwspindie 8. To control the amount of this" ad iustment I provide a wheel9 (Figs. 1, 2) having a division and a scale 9* Fig. 1) with vernierfixed to the guide 2 for the slide A drag mechanism comprising screwspindles 11 and 12,which are provided with a right-handed and alefthanded thread respectively, effects the movement of the slide 4 inthe transverse direction. The screw-thread of the spindle 11 has asmaller pitch than the screw-thread of the spindle 12 and said spindle11 carries a spunwheel 13 (Figs. 2 and 31). Both. these spindles 11, 12mesh with nuts 4" ig. 26) fixed to the'slide 4. The other end of thespindle 11 carries spur-wheel 14, which meshes with a spur-wheel 15(Figs. 1, 2, 26). he iatter is on a sleeve 17 (Fig. 26). This sleeve 17and a number of friction disks 18 are :r E- idly connected to the Y )Ildisks 16 are rigidly 15. These disks 16 against one another by means ofan adj stable part 15. Thus, it will be seennow, that on a rotation ofthe spindle 11 the spindle 12 is also rotated owing to the frictionproduced between said disks, the speed of rotation of the spindle 12being thereby smaller than that of the spindle 11, as the diameter ofthe wheel 15 is considerably greater than that of wheel 14. In any casethe movement of spindle 12 is always determined by'the movement impartedto the slide 4 brought about by the spindle 11, said spindle 12 takingup the play between the spindle 11 and the nut 4 meshing with thelatter.

The cross slide 4 carries the round table 19 (Figs. 2, 3, 27) having aworm-wheel rim. The latter engages with a worm 20 (Fig. 27) adapted toslide in the key way of a shaft 21. One end of this shaft 21 carriesmoreover a brake device acting by friction (Fig. 27), which'acts toprevent accelerations of said shaft. This brake device causes achangegearing 22 (Fig. 31) operatively connected to this shaft andcomprising a spur-wheel 22 (Fig. 3) to oppose a greater resistance torotation than a pair of planet toothed wheels 35, 36 (Fig. 20) ofmechanism fitted within a table box and 2 fuily later on. Said brake dca sleeve 23 (Fig. 27) fixed to the shaft 21 i spindle while if iconnected to the W1 'scri bed inc pressed working against the front sideof said sleeve 23 by a spring 24*. The disk 24 is adapted to be movedlongitudinally in a key way of a stationary bush 25. Y

T able b0x.The shafts 11, 12 and 21 are operatively connected in such amanner by means of two change-gearings 22 and 22 Fig. 31), that therequired rolling movement will be imparted to the blank. The control ofthis movement is effected by two shafts 26 and 27 (Figs. 2, 3, 7, 8, 9)extending toward the rear end of the machine.

.to be moved in the axial direction of this shaft. On'each side of thissleeve 28 is also mounted on the shaft 26 a bevel-wheel 29 and 30respectively, having each a long hub surrounding the shaft 26. Boththese wheels 29 and 30 have on their inner side clutchteeth. They meshmoreover with a bevelwheel 31, which is rigidly connected with The shaftactuates the change-gearings spur-wheel 31* and fixed to a short shaft I32. The whole hereinbefore described gearing constitutes a reversinggearing for driving the shaft 32 in both directions while the shaft 26is eonstantl revolving in the same direction. The sha t 32 forms so tospeak the front pin of a bevel-wheel 33, the rear pin of which carries aloose bevel-wheel 34 rigidly connected to a spur-wheel 54. Between thetwo wheels 33, 3-1 are arranged two planet-wheels 35 and 36 meshingtherewith, the whole forming a planet bevel-gearing. The ring 37, actingas a bearing for the wheels 35 and 36, has a hardened cam groove 38(Fig. 19) adapted to be engaged by a pin 39 of a lever 40 (Figs. 19,20), which is formed integral with a lever 41 (Figs. 19,

49 meshing with an end of said shaft 47 havin the form of a rack.Smr-wlieel 49 is The latter is moved in its turn in v fixed to a shaft50 (Figs. 1, 3, 19, 20). The

above mentioned spur-wheel 31 meshes with a spnr-w l *l 20). which isfixed to a shaft carrying at its other end a spurwheel 53 fixed thereto.This wheel 53 constitutes the drivin wheel of the pitch change-gearing22 see also Fig. 31), which drives the shaft 11, while the spur-wheel 54(Figs. '3, 20, 31) forms the driving member of the change-gearing 22,which drives the shaft 21. y means of a crank lever 55 (Figs. 1 and 3)fixed to the shaft 50, the clutch sleeve 28 may be clutched to either ofthe bevel wheels 29 or 30, or not clutched at all, corresponding to therolling movement of the table in the two directions or the stolgping ofall table movement. 1

rive.- (Figs. 2, 3, 5) denotes a pulley, which constitutes. the maindriving member of the machine and which forms at the same time the outerpart of a friction clutch. The inner part 61 of this clutch is fixed toa shaft 62. To this shaft 62 is also fixed a wheel 63 of a bevel-gearing63, 64 (Figs. 2, 5). The other wheel 64 of this gearing is mounted on ashaft 65 (Figs. 2, 4) driving a shaft 66 (.Figs. 1, 2) through thechangewheels 66, 67, 68, 69, 70, 71, 72, 73 (Fig. 4). For the purpose ofthrowing these changewheels in and out of actionI provide toothedwheel-sleeves 74, 75 (Fig. 4) and pinion segments 76, 77 (Figs. 4 and1), these seg ments being operatively connected-to handles 78 and 79 bymeans of shafts 80 and 81 respectively.

("utter m0vement.The front end of the shaft 68, which I shall now callhereinafter the cam-disk shaft.' terminates in a cam-disk .82 (Figs.1,2, A gudgeon 83 acting as a bearing for a block 90 is adapted to bemoved in a radial direction relatively to said disk 82 by means of ashaft 85 having a squared end 84 (Figs. 1, 2, 6), bevel-gearing 86, 87(Fig. 1) and thread spindle 88. Nuts 89 serve to secure said gudgeon indeterminate positions.

The block 90 (Figs. 1, 2, 3) mounted on the gudgeon 83 slides in a slotof a link 91 (Figs. 1, 2, 3) pivotally mounted on a pin 92 (Fig. 2). Toa pin 93 (Fig.3) of this link 91 is operatively connected a crank rod94, which comprises a safety break sleeve 95 and which imparts to a ram97 (Figs. 1, 2) a vertical reciprocating movement. this ram 97 ispivotally mounted the cutter holder 98 (Figs. 1, 22, 23, 24). The rammay be adjusted vertically by means of a shaft 99 (Fig. 1) having asquared end, a bevel-gearing 100, 101 and a screw spindle 102. while anut 103 (Figs. 1 and 2) serves to secure this ram in its properposition.

The pin 92 carrying the link 91 is mounted in a movable part 300 (Figs.1 and 2), to which is secured a guide piece 300* (Figs. 2, 3, and 23)for said link. This part 300 has also a guide for the ram 97 and it isadapted to be moved into an oblique posi tion for the purpose of cuttingscrewand double helical spur-wheels by means of a worm gearing 300, inwhich position it may be fixed by means of screws 300' (Fig: 1). Thecutter holder 98 carries the multipletooth cutter 104 of rack form (Fig.2). A spindle 104 (Fig. 22) provided with a leftand right-hand threadpasses through two wedges 400 (Figs. 22, 23), which upon a rotation ofsaid spindle 104 may be moved toward one another for the purpose offixing the cutter 104 in the holder 98. The upper and lower sides ofsaid wedges 400 have also a different inclination, so that the cutter104 is pressed downward on its holder 98. As the cutting tool has to beprevented from coming in contact with the blank on the return stroke,the cutter holder 98 is pivotally mounted on a pin 105 (Figs. 1, 23,24). A toothed segment 106 (Figs. 23, 25) is formed integral with saidcutter holder 98 and it meshes with a toothed part of a sleeve 107. Thelatter is loose on a shaft 108 (Fig. 22), but is provided with frictiondisks 109 fixed thereto; These disks work together with friction disks110 keyed to theshaft 108. The latter carries. on one of its ends atoothed wheel 112 which meshes with a rack 112 (Figs. connected to theguide of the ram. On a vertical movement of the ram 97 the wheel 112meshes with said rack, it being thereby moved in the longitudinaldirection of the latter, and owing to the friction produced between thedisks 109 and 110 an oscillating movement is then imparted to thetoothed segment 106 until the latter comes to rest either on the pin 106or the surface 106 (Fig. 111 (Figs. 22, 23) area number of wheelsadapted to be moved simultaneously for the purpose of effecting an exactparallel adjustment of the cutter 104 by means of a shaft 111 (Fig. 23).In order to eliminate all shocks, which might arise owing to the play inthe driving mechanism, particularly between the link 91 and the block.during the upward and downward movement of the ram 97, I connect to thisram a heavy balancing weight 113 (Figs. 3, 1) by means of a member 114.

eed mechanism.The rear end of the cam-disk shaft 68 carries anelliptical spur- Wheel 1120 (Figs. 1, 2, 6, 28) meshing with 115 anelliptical wheel 121 mounted on a short pin. \Vheel 121 is formedintegral with a part having the shape of a bevel-wheel and engaging witha bevel-wheel 122 (Figs. 2, 5). This is loose on a feed shaft 123 (Fig.29), carrying thefeed crank-disk 124. The boss of the Wheel 122 hasclutch-teeth, which engage with corresponding teeth of a clutch'member340 (Fig. 29) fixed to the shaft 123 and adapted to be moved in the 125longitudinal direction of the latter. The clutch-teeth of said members122. 340-are caused to mesh by a spring 340 (Fig. 29) acting on themember 340. This clutch 122, 340 secures a proper feed, as on theoccurring of trouble in the feed mechanism the teeth of the members 122,340 are causedtc disengage one another, sothat the crankdisk 124 remainsstationary. A. short crank rod 125 connects the disk 124 to a link 126(Figs. 1, 5). A slide 127 is adapted to be moved radially within thislink 126. The movement of the slide 127 is transmitted to a plate 129(Figs.v 1, 5) by means of a rod 128. The plate 129 carries a pawl 136adapted to engage a feed-wheel 131.

Owing to the fact, that the abox e described link mechanism 91, 94 formoving the ramv 97 effects in less than half a revolution of the shaft68 an upward movement of said ram, it will be seen, that the feedmovement would artly coincide with the course of work of the cutter, ifthe above mentioned elliptical wheels 120 and 121 (Figs. 1) did notpermit the shaft 123 to carry out a revolving movement, which isproportional to the feed stroke, for the purpose of effecting the feed,only during the return stroke of the ram.

Control mechanism.-The shaft 132 (Figs. 1, 5, 7) carrying the feed-wheel131 has on that side of the machine, on which is mounted the ulley 60, aspur-wheel 133 (Figs. 5, 9) mes ing with a spur-wheel 134' (Figs. 8, 9).This wheel 134 is rigidly connected to a sleeve 134 acting as a bearingfor a shaft (Figs. 8, 9, 15), on which is a loose'bevel-wheel 136, abevel-wheel 135 hasa long sleeve 167 loose on the sleeve 134. The one orthe other of these bevel wheels 135, 136 drives a bevel-wheel 137 fixedto a shaft 141 8, 9), which drives the shaft 26 (Fig. 8) through aspurwheel gearing 141, 141 (Fig. 8). On the termination of a course ofWork, that is, after one or more pitches have been rolled past thecutter 104*, the latter is, as already stated, stopped in its uppermostposition while the blank is moved back into the new working position.Hereinafter I shallcall 1 ment is started through an automatic mechanismcomprising adrum (Figs. 7, 8,

9, 10) and described more fully later on.

On the circumference of said drum 150 are provided a number of cams A,B, C, D, E, F, (Figs. 12, 13, 11). The drum 150 is mounted on a shaft151 (Figs. 8,7 and it has on each side a driving plat e.' 1 Each ofthese plates has a driver or catch 152 and 153 respectively -(seealsoFigs. 15, 16, 17, 18), the outermost position of which is determined bybolts 154 projecting into slots of these drivers. The outer'end of eachdriver 152', 153 respectively has the form of a pawl and they are'causedto work together with cams 155 (Figs..15 and 18) fixed to spur-wheels156 and 157 by springs. which tend to move these drivers in a. radialranged. within the driver 152 may be re movement are driven by a pulley174 (Figs.

direction. A pin 159(Figs. 15, 1e) artracted by means of a hand lever158 (Fig. 8) operatively connected to a member 158 and a shaft 160(Figs. 8, 9, 15,16) for the purpose of bringing said driver out of reachof the cams 155 and of disconnecting the drum 150 from its drivingmechanism. As will be seen later on, no reversing move ment takes placein this case. lhprefer to provide also additional means to permit thestarting'of this reversing movement by hand, as on the cutting of thefirst teeth of a blank the cutter has to be moved from the side towardsaid blank until several teeth of the cutter of rack form are able toout before any reversing movement may be imparted to the blank.

The spur-wheel 156 receives its drive through the'wheels 161, 162, 163(Fig. 8),- while the spur-wheel 157 is operatively connected to thewheels 164, 165, 166. Wheels 163 and 166 are fixed to the sleeves 167and 168 of the bevel-wheels 135 and 136 respectively, having on theirinner side clutchteeth. These teeth are adapted to mesh alternately withtwo clutch-sleeves 169 and 170 (Fig. 8) mounted on the shaft140 betweenthe sleeves 167 and 168, the sleeve 169 being rigidly connected to thesleeve 134, while the sleeve 170 is adapted to be moved in a key-way ofthe shaft 140. A bevel-wheel 137 fixed to' the shaft v141 meshes withthe two bevel-wheels 135 and 136. Shaft 141 is, as already stated,operatively connected to the shaft 26 by means of change-wheels 141, 1417, 8) adapted to be moved into the operative position by means of a handlever. 142 (Figs. 1 and 4), shaft 143 (Figs. 7, 9) and a fork- I likemember 144, the speed of the momentary rolling movement, and thereforealso the number of the pitches of the blank rolled past the cutter 104"during a course of work of the machine, depending on the 11 diameter ofthe change-wheels, which are just brought into the operative position.

The members for effecting the reversing 2, 7, '8), which is driven inits turn by a 11 pulley 173 (Figs. 2, 3) fixed to the main shaft 62. Theshaft of the pulley 174 carries on the other end a pinion 17 5 (Fig; 8)meshing with a toothed wheel 176 and the latter engages in itsturn .witha toothed wheel 177 12 u fixed to the above mentioned shaft 140 (Fig.8). On a rotation of the control drum 150 the cam F of the latteractsupon a lever 178 (Figs. 12, 7, 8, 9), which is fixed to the shaft 27already referred to, so that a small 125 oscillating movement is thenimparted to said lever 17 8 and therefore also to this shaft 27. Thisinfluences the parts 44, 41, 40, 39

(Figs. 19, 21) in such a manner, that the ring 37 acting as a bearingfor the planet 180 mps bevel-gearing arranged in the table box isreleased, so that the revolving movement of the table carrying the blankis interrupted.

The cams A and B (Figs. 12, 13) of the drum 150 are adapted to pushaside a lever 179 (Fig. '7), which imparts thereby a rotation to avertical pin 180 and a lever 181.

.The latter forms a toggle-lever, which is acted upon by a spring. Asthis lever 181 is also adapted to oscillate about a gudgeon 182 (Figs.7, 8), the lever 179 has to be moved by said cams A and B only alittleout of its (Fig. 10) of a lever 185 (Figs. 10, 7). The

lever 185 having a fork-shaped part 185 (Fig. 10) causes that one of thetwo clutchsleeves 169, 17 0, which is just clutched to one of thebevel-wheels 135 or 136 to disengage said wheel, while the other one ofsaid sleeves is then clutched to the corresponding bevel-wheel. Thus itwill be seen, that bevel-wheel 137 imparts to the shaft 141, andtherefore also to shaft 26, a determinate direction of rotation, towhich corresponds a determinate rolling movement of the table carryingthe blank. Moreover, the lever 185 is able to pivot only to a certainamount in the direction toward the pulley 174 after lever 179 has beenacted upon b cam B, as its hooklike projection 186 ig. 10) engageswith.a projection 187 (Fig. 11) of a lever 187 upon the oscillation ofsaid lever 185 through a certain angle. Said lever 185 may be movedwholly to the left and cause a clutching of one of said sleeves 169, 170only upon a falling of the lever 187. The falling of this lever 187 isbrought about by a cam 206 (Fig. 5) fixed to the shaft 68 and actingupon the lever 187 through a mechanism described more fully later on. Asthe movement of the control drum 150 has to be independent of the cuttermovement and the feed movement and. as the reversing movement has tobegin While the ram 97 is in its uppermost position, I usethe cam shaft68 effecting the movement of the ram for imparting a downward movementto the lever 187 in order to control the beginning bf the reversingmovement. p

A recess in the cam D (Fig. 12) of the drum 150 admits an inwardmovement of a bolt 188 (Figs. 9, 7, 13) acted upon by a spring, whichmovement causes a rotation of a lever 189 (Figs. 7, 8), a pin 190 and aclutch lever 191 (Fig. 2), so that a clutchmember 192 (Figs. 2, 8, 9)fixed to the shaft 140 is caused to mesh with the spur-wheel v177(Fig.8).

134. In this case the wheel 134 is no longer driven by the feed-wheel131 (which is now stationary), but it is then moved at the same speed ofrotation as the shaft 140, which is moved in a uniform manner by thereversing pulley 174 through toothed wheels 175, 176, It is evident,that in this case also feed-wheel 131 has to take part in the quickmovement of the wheel 134, whereby the feed pawl 130 slides over theteeth of said wheel 131. Moreover, also shaft 141' and therefore alsoshaft 26 as well as the drum 150 have a than usual.

The cam C (Fig. 12) of the drum 150 is adapted to lift the lever- 187,which causes thereby a rotation of a shaft 194 (Figs. 11, 12, 5 and 6)and an upward movement of a levegarm 195 (Figs. 6, 5). The latter isoperatlvely connected to a vertical rod 196 acted upon by a spring andpivoted to a lever 197 (Fig. 5), which may be caused to oscillate bysaid rod 196, in order to act upon the part 61 of the friction clutch60, 61. An oscillation of said lever 197 causes at the same time arotation of a segment 255 (Figs. 5, 30) which meshes with. a toothedsegment 255 (Fig. 30) operatively connected to a brake band 200, so thatthe latter will be untensioned or tensioned according to the directionof rotation of the segment 255. These different parts are secured in theosition shown in Fig. 5 by the edge 201 Fig.

greater speed of rotation 5), which the pawl 202 acted upon by a Inorder that the stop 204 may be moved; only at a certain predeterminedinterval" during a rotation of the shaft 68 toward the disk 205 Iprovide a suitable locking mechanism, which comprises a lever 211 (Fig.5), acting once during each revolution of the cam shaft 68 upon a springbolt 212, and a pawl 213 connected to the latter. According to theposition of this pawl 213 the stop 204 is either locked inja determinateposition or it is then released.

A rotation of the lever 197 (Fig. 5), that is a rotation of theprojection 214 of-this lever, allows also a rotation of the cam 215.

The latter is caused to oscillate by a spring 216 (Fig. 2), whichismounted on the shaftof a handle 217 (Figs. 2, 4) and which acts on amechanism, transmitting the pressure of said spring to the cam 215 inthe direction of the arrow 218 (Fig. 5). Thus, the cam 215 serves tocontrol the starting of the machine, while the stop 219 serves tocontrol the stopping of the machine. In Figs. 1, 5 and 6 it will beseen, that the movement oftthe cam 215 in the direction of the arrow218i influences the machine in the Same manner as the lifting of thelever 187. When the machine has to be stopped by hand, the shaft22Q-ismoved in the direction of thearrow'221 (Fig. 5), the stop 219 pressingon the lever 222, so that the small pawl 202 releases the rod 196, whichis then pressed downward, owing to the action of its spring, causingthereby a throwing out of gear of the friction clutch 60, 61 and atensioning of the brake band 200. As the handle 217 through the stopmechanism acts on the brake, it is clear that the machine can only bestopped by this handle during the cutting and not during the reversingperiod, at which time the clutchis already released.

The toothed clutch 224 6) opera-- tively connected to the member 121 maybe put out. of action by means of lever 223 (Figs. 2, 5, 6) in whichcase said spurand bevel-wheel 121 (Fig. 6) is no longer rigidlyconnected to its shaft. The feed crank-plate 124: can thus be displacedwithout the disk of the shaft 68 effecting a movement of the ram beingrotated, so that thepoint of time, at which the feed takes place, may beadapted in any suitable manner to the cutter stroke.

The blanks are centered as a rule on a mandrel of the table 19 and theyare clamped tightly by a nut.

I .shall now explain the working of the hereinbefore described machine.This may be best explained by the description of one complete course ofwork of the machine.

The sequence and the duration of the different table movements areillustrated diagrammatically in Fig. 14. As all these,

movements are controlled by the drum 150 I reserve for each operation acertain stretch of a revolution of the drum, it being understood, thatthe drum describes one complete revolution during a complete course ofwork,

(5) During 4/10 of a drum revolution:

A step by step forward rolling movement. It is thereby asumed, that theforward direction is the direction of movement during the cuttingperiod.

Movements (1), (2) and constitute the reversing movement, movement (4)serves to take up the play and movement (5) constitutes the so-calledcutting period. Y Notwithstanding the fact, that only 4/10 of arevolution of the drum 150 are reserved for the cutting period, th'etimerequired for the reversing and the taking up of the play amounts only toabout 1/10 of the time of a-cutting period, as the drum 150 and thetable 19 have during said four first movements a much greater speed thanduring the cutting period. For the rest, only the second and the fifthof these movements are theoretically absolutely necessary. As the blank,receiving during the cutting period a rolling motion is fed past themutiple-tooth cutter of rack form to an amount corresponding to one orseveral wholepitches and as the cutter has but a limited length, thecenter of the blank has to be moved back into the original position,without the blank being rotated, as soon as a cutting 'period isfinished. This is the reason why I impart to the table the movement Inorder to obtain practically in a secure manner an accurate work I rollthe table at first twice backward. during 1/20, that is totally during1/10 of a revolution of the drum beyond the starting posi tion andafterward during 1/10 of a revolution of the drum 150 in a forwarddirection. The result of this is, that any play between the movableparts is eliminated in the direction of the forward rolling movement.Why I prefer to impart to the blank twice a backward rolling movementlasting each l/20 of a revolution of the drum instead of only one suchmovement lasting 1/10 of a revolution of the drum I shall explain lateron. I

Let it be now assumed, that the machine is working at the end of thecutting-period. The main driving shaft 62 drives the cam disk shaft 68*,as the parts 60, 61 (Fig. 5)

.of the friction clutch mounted on this shaft 62 are in their operativeposition .while the brake band 200 is not tensioned, so that a verticalreciprocating movement is imparted to the cutter, while a periodicalrevolving movement is imparted to the feed-wheel 131. Each shortmovement of this feedwheel 131 is transmitted aoh time to the shaft 141through the shaft132 (Fig. 5) the spur-wheels 133, 134 and bevel-wheels135, 137 (Fig. 8) and from said shaft to the shaft 26 mounted in thetable box through the change-gearing 141 141 (Figs. 7, 8). Said shaft 26drives (according to the direction of rotation) either the bevel-wheel29 or 30 as well as the bevel-wheel 31 and the spur-wheel 31" andtherefore also the shafts 32 and 52. The latter transmit their drive tothe shafts 21 and 11, 12 respectively through the two change-gearings22", 22 (Fig. 31). These shafts impart then each time a small rollingmovement to the table the provision of the change-gearing 135,

It is evident, that bevel-wheel 136 isalso moved on each feed stroke andhence also spur-wheels 166, 165, 164, 157. The latter rotates in adirection opposite to the direction of rotation of the drum driver 153.As, however, the cams 155 provided on the Wheel 157 do not strikeagainst the radial front part, but against the curved front side of thedriver 153 (Fig. 18), the latter is only moved inward,-so that the cams155 may slide over this driver 153 on a rotation of the wheel 157.Shortly before the last feed stroke of the cutting period is carried outthe cam E ofthe drum 150 is just passing beneath the projection of. thelever 210, which by reason of spring 207 on rod 207 (gig5) is caused toenter the recess in cam so that the rod 207 (Fig. is lifted against theaction of its spring 207*, while the stop 204 is oscillated about thepivot 252 and thus moved within reach of the cam 206. The last feedstroke has the effect of moving the beginning of the cam B of the drum150 beneath the lever 179, which is thus pushed aside by said cam. Owingto this, the clutchsleeve 169 (Figs. 7, 8) is caused to disengage thebevel-wheel 135, so that the drum 150 ceases to rotate. At the same timethe lever 185 (Fig. 10) causes a tensioning of the spring of thetoggle-lever 181 (Fig. 7) without the latter being, however, able tomove wholly toward the other side, as the nose 187 of the lever 187prevents for the time being a further rotation of said lever 185. In themeantime the cam 206 (Fig. 5) on the cam disk shaft '68f is movedbeneath the stop 204, which is just rotated about the pin 253 (Fig. 5)at'the moment at which the ram 97 reaches its uppermost position. Therod 254 (Fig. 5) is thus raised, the right hand end of "crank lever 222is depressed and the pawl 202 is moved away from the edge 201. The rod196 is now depressed owing to the action of its spring and lever 197throws the friction clutch 60, 61 out of gear and tensions the brakeband 200 by means of the bevelwheel segments 255 and 255 (Fig. 30), sothat the main shaft 62 and therefore also the movements of the cutterand the feed movement are suddenly stopped. Moreover, the cam 215 ismoved in the opposite direction of arrow 218 (Fig. 5) and the handoperated stopping device comprising handle 217 (Figs. 2, 4) is released.A few moments after the moving of stop 204, the cam E again acts on theprojection of the lever 210 and presses the lever down as well as rod207.

The falling of the rod 196 causes also an oscillation of the lever 187toward the drum 150, so that the tensioned spring of the toggle-lever181 (Figs. 7, 8) exerts now its action upon. the latter, which isoscillated and clutches the sleeve 170 to the bevel-wheel 136'. As,however, the reversing pulley 174, and therefore also the shaft 140, areconsta'iitly rotated in the same direction, the bevel-wheel 136 rotateswith the same speed of rotation as "the shaft 140 and it transmits itsmovement to the shaft 26 through thechange-gear 141*, 141 This shaft 26is, however, moved in the opposite direction, so that it imparts to thetable 19 backward rolling movement. The bevel-wheel 136 drives now thespur-wheels 166, 165, 164, 157 (Fig.

8). The latter actuates the driver 154 and thus also the drum 150, whichis rotated in the same directiomas before. Upon 1/20 of a revolution ofthe drum 150'the cam F of this drum pushes the lever 178 aside, so thatthe shaft 27 mounted in,the table box is rotated. Owing to this, thelever 46 (Fig. 21) in the table box is raised and the pin 39 of thelever 40 (Fig. 19) is withdrawn from the recess 38 of the planet ring37. The con-- stantly rotating shaft 32 is then prevented from drivingthe wheel 34 (Fig. 20), but it drives now the ring 37 together with itstwo bevel-wheels 35 and 36. Thus, the backward rolling movement of thetable 19 is arrested as the wheel 54, and therefore the shaft 21, are nolonger rotated and the table 19 carries out only a backward travel. Thistravel lasts 4/10 of a revolution of the drum, the planet ring 37completing during this time just one revolution, whereupon its recess 38is again moved beneath the pin 39. In the meantime the cam F has beenmoved farther and the springs 43 and 45 push after a certain timeintervalthe pin 39 again into the recess 38, so that the planet ring 37is arrested, while the shaft 27 and the lever 46 are returned into theirearlier position. As soon as the planet ring 37 is held fast, thebevel-wheel 34 is of course again rotated, so that the table 19 receivesa backward revolv ing movement. As the straight backward travel of thetable has not yet been inter- 'rupted, a new backward rolling movementis pleted and I shallnow explain why I prefer stead of only one lasting1/10. The reason therefore is, that I wish to be quite certain that thepin 39 of the lever 40 engages in a at which the pin 39 should engagethe-recess 38, so that this pin 39 would have only a very short timeinterval at its disposal for engaging said recess. Shortly before thesecond backward rolling movement is com- 'pleted,a recess of the cam Dof the drum 150 is moved in front of the bolt 188 (Fig. 9), which ispressed into said recess by a spring causing thereby the throwing intogear of'the clutch 192 (Fig. 8), so that the spur-wheel 134 and thetoothed sleeve 169 are now rigidly connected tothe shaft 140.-

At the beginning of themovement serving to take up the play the cam A ofthe drum 150 moves the lever 179 toward the side of the pulley 174,coupling thereby the sleeve 169 to the sleeve of the bevel-wheel 135. Asthe sleeve 169 is at this time also connected to the constantlyrevolving shaft 140 by means of the afore-mentioned clutch-192, thebevel-wheel 135 has now the same speed of rotation as the shaft 140fandit drives besides the bevel-wheel 137 the shafts 141 and 26, but, aswill be seen in Fig. 8, in the oppo-- of the feed-wheel 131, the teethof whichmay move unhinderedbeneath the pawl 130. In the meantime therecess in the cam D has been moved through a certain angle and the.bolt' 188 is then again pressed out of said recess and the clutch- 192thrown out of gear,

so that the clutch-sleeve '169 is uncoupledfrom the. shaft 140. The drum150 and the takinfiup' 4. a gear-cutting machine, in combinatable19-would now'remain stationary, but

as the cam C of the drum 150 has again been moved within reach 0f thelever 187*,the latter, and therefore also the rod 196, are raised,imparting'therebyan oscillation to the lever 197, so that the brake band200 is l ntensioned and the friction. clutch 61, 62 thrown into gear,whereupon the movement of the ram 97 andthe feed movementare againstarted, that is, anew cnttingperiod position.

is started. At the same time the spring 203 causes the pawl 202 toengage the edge 201,

so that the rod 196 is fixed in a determinate An oscillation of thelever 214 causes also an oscillation of the crank lever 215, whichreturns the hand operated stopping device into the starting position.Now,

it will be seen, that the difierent parts of the machine take then upthe same'positions as it has been assumed they had, when I started todescribe the working of the machine, that is, the machine has nowcompleted a course of work. During this time the blank has been rolledpast the multiple-tooth cutter of rack form to an amount correspondingto an integer number of pitches.

What I claim is:

1. In a gear cutting machine, a multiple tooth cutter. of rack form, areciprocable holder therefor, a blank carrier, means for.

rolling the blank past the cutter an integral number of pitches duringthe cutting operation, means for arresting the rolling of the blank at apredetermined point, and means for moving the blank back past the cuttera distance equal to the rectilinear travel of the before-mentionedrolling move ment.

2; In a gear cutting machine,'in combina i tion, a multiple-tooth cutterof rack form, a reciprocating ram carrying said cutter, a blank-carrierand means ada ted to impart to the latter a step by step-r01 ingmovement during the cutting operation past the cut- .ter to an amountcorresponding to an integernumber of pitches and mechanism to effectbetween such succeeding operations an additional forward and backwardrolling movement past' the'cutter totake up the play in said meansformoving the blankcarrier,'these additional movements being. carriedout with a greater speed than the movementof the blank-carrier duringthe planing operation.

3. In a gear cutting machine, in combination, amultiple-tooth cutter ofrack form, a ram carryingthe latter, a blankcarrier, an intermittentlyworking main driving member im arting the movement to the cutter and thelank-carrier during the cutting operation and a constantly running a'ving member moving only the blank-carrier d' the period 0 reversing andd ditional movementv for ep'lay in the mechanism.:

tion, afcutter, a carrying the latter, a movable blank-carrier, meansadapted to move said ram and blank-carrier and a central control-drumadapted-t0 control said means, substantiallyas described.

5. In a gear-cutting machine in combination, a cutter, a ram carryingthe latter, a blank-carrier, a main drive, a cam-disk shaftintermittently driven by the main drive, means actuated by. said shaftfor moving the ram and the blank carrier, a central control+ drum forcontrolling the movements of said means and means for driving said drumby said shaft during the cutting operation. 7

6. In a gear-cutting machine, in combination. a cutter, a ram carryingthe latter, a blank-carrielg a main drive, means actuated by the maindrive for moving said ram and the blank-carrier, a drum for controllingthe movements of said means and an au-X- iliary drive and auxiliarymeans adapted to move the control drum during the movements outside thecutting operation, substantially as described.

7. In a gear-cutting machine, in combination, a multiple-tooth cutter ofrack form, a ram carrying the latter, a blank-carrier, a main drivingmember, a cam-disk shaft intermittently driven by said member, meansactuated by said cam-disk shaft for moving the ram, means actuated bysaid shaft for imparting to the blank-carrier during the cuttingoperation a rolling movement past the cutter to an amount correspondingto an integer number of pitches, a constantly running auxiliary drivehaving a greater speed of rotation than said intermittently driven shaftand adapted to impart a straight reversing movement to the blankcarrierand a movement adapted to take up the play in the means moving theblankcarrier and a control-drum controlling the movements of all saidmeans, said drum being driven during the cutting operation by saidintermittently driven memberand during the reversing movement of theblankcarrier and said movement adapted to take up the play by saidauxiliary drive, substantially as described.

8. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a

blank-carrier, means for moving said ram and blanlccarrier and a drumfor controlling said means and effecting one complete revolutionduringone course of Work of the machine, substantially as described.

9: In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and blank-carrierand a drum for controlling said means rotating only in one direction,while the means controlled by it revolve in different directions,substantially as i described.

10. In a gear-cutting machine, in combination. a cutter, a ram carryingthe latter, a blank-carrier, means for moving the carrier and rain. adrum for controlling said means and adapted to be driven by the latter,and hand operated means for disconnecting the drum from said drivingmeans without interrupting or influencing the momentary movement of theblank-carrier, substantially as described.

11. In a gear-cutting machine, in combination. a'cutter,a rain carryingthe latter, a blank-carrier, means for moving said blank carriercomprising a feed shaft, a

group of change gearings for imparting a traveling movement to theblank-carrier and a second group of change gearings for imparting arevolving movement to said carrier, and means for automaticallyoperating the first said group of change gearings alternately inopposite directions, substantially as described.

12. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said blankcarriercomprising "two groups of change-gearings adapted to impart to theblank-carrier a revolving and a forward and backward traveling movementrespectively, and members adapted to automatically arrest thechange-gearing effecting the revolving movement during the backwardtravel of the blank-carrier, substantially as described.

13. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving .said ram and imparting tothe blank-carrier a rolling movement, a revolving movement and alongitudinal travel, said means comprising a reversing gearing adaptedto reverse by hand said rolling movement, the revolving movement and thelongitudinal travel, substantially as described. lei. In a gear-cuttingmachine, in combination, a cutter, a ram carrying the latter, ablanlecarrier, means for moving said ram and blankcarrier and handoperated means to interrupt at any time the movement of theblank-carrier without interrupting the movement of the ram,substantially asdescribed.

15. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and imparting tothe blank-carrier a rolling movement past the cutter, and hand operatedmeans adapted to vary at any time the velocity of said rolling movementwithout stopping the machine, substantially as described.

16. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and blank-carriercomprising a worm shaft adapted to impart a revolving movement to theblank-carrier and a brake'device on said Worm shaft, substantially asdescribed.

. 17. In a gear-cutting machine, in combination, a cutter, a ramcarrying the latter, a blank-carrier, means for moving said ram, andmechanism formoving the blank-carrier comprising a drag spindle deviceadaptedto take up the play in said mechanism, substantially asdescribed.

18. In av gear-cutting machine, in combination, a cutter, aram carryingthe latter, a blank-carrier, means adapted to move said ram and impartto the blank-carrier a rolland a movement for taking up the play in themeans for moving the blank-carrier during the interruption of thecutting operation and means adapted to arrest the ram and its drivingmechanism during the reversing movement and the movement for taking upthe play outside the blank in order to pre Vent the cutter from engagingthe blank, substantially as described.

19. In a gear cuttingmachine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and theblank-carrier, a central drum for controlling said means, means adaptedto arrest the ram while the blank-carrier is moved, and means controlledby said drum adapted to prepare the arresting of the ram, substantiallyas described.

20. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and theblank-carrier, a central drum for controllingsa-id means, means adaptedto arrest the ram. while the blank-carrier is moved, nieans controlledby said drum adapted to prepare the arresting of the ram, and membersadapted to lock the last mentioned means While the cutter is within theblank, substantially as described.

21. I a gear-cutting machine, in combination, a-cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and blank-carriercomprising a main drive,

.a cam-disk shaft and a clutch adapted to transmit the movement of themain drive to said cam-disk shaft, and means actuated by the latter torelease the clutch and means to suddenly arrest the movement of the ramWhile the cutter is outside the blank and the clutch is released,substantially as described. v

22. In a gear-cutting machine in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and blank-carriercomprising a main drive, a cam-disk shaft and a clutch adapted totransmit the motion of the main drive to said cam-disk shaft and a brakeadapted to arrest immediately the movement of the ram on a throwing outof gear of said clutch, a central drum controlling said means, and meanscontrolled by said drum adapted to throw said clutch into gear andrelease the brake for the purpose of restarting the am movement,substantially as described.

23. In a gear-cutting machine, in eom bination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and imparting tothe blank-carrier a rolling movement past the cutter during the cuttingoperation, a reversing movement and a movement fontaking up the play insaid means for moving the blank-carrier, and hand operated means tomomentarily arrest ing means to prevent the starting of the' reversingmovement before the ram is arrested, substantially as described. I

25. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, and means for moving said ram and theblank-carrier comprising a main drive, a cam-disk shaft driven by thelatter and adapted to move the ram, a feed shaft for moving theblank-carrier, and a pair of elliptical toothed Wheels for transmittingthe movement of said' cam-disk shaft to the feed shaft, substantially asdescribed.

26. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving said ram and theblank-carrier comprising a feed mechanism having a feed link and amember manually adjustable relatively to said link, the feed movementbeing adapted to be varied while the machine is in operation on anadjustment of said member, substantially as described.

27. In a gear-cutting machine, in combination, a cutter, a ram carryingthe latter, a blankcarrier and means for moving said ram andblank-carrier comprising a feed mechanism for the blank-carrier and asafety clutch adapted to stop said mechanism on the occurring oftrouble, substantially as described.

28. In a gearcutting machine, in combination, a cutter, a ram carryingthe latter, a blank-carrier, means for moving the ram and theblank-carrier comprising a camdisk shaft, a feed shaft operativelyconnected to the blank-carrier and adapted to be driven by said cam-diskshaft and a clutch between said shafts to permit the movement of the ramto vary relatively to the movement of said cam-disk shaft in ordereffect the generation of gear teeth on the blank, means for moving thecarrier rectilinearly backward through a distance equal to an integralnumber of pitches, and means for interrupting the normal operation ofthe tool holder with relation to the blank-carrier after each forwardrolling movement and for starting the said'normal operation after eachbackward rectilinear movement.

30. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder normally reciprocating in a fixed path andadapted to hold a cutter of the rack type, means for rollingthe carrierforward with respect to the tool-holder to effect the generation of geanteeth on the blank, means for moving the carrier rectilinearly backwardthrough a distance equal to an integral number of pitches, and meansgofor stopping the reciprocation of the tool holder'after each forwardrolling movement and for starting the said reciprocation after eachbackward rectilinear movement.

31. An automatic gear cutting machine comprising'in combination ablank-carrier, a tool holder reciprocating in a fixed path and adaptedto hold a cutter of the rack type, two controlling mechanisms actingsuccessively and alternately, one mechanism serving to simultaneouslyturn the carrier forward and to move it rectilinearly forward whereby aforward rolling movement is effected and the other mechanism'serving toturn the carrier backward and to move it rectilinearly backward, thebackward rectilinear movement exceeding that necessary for backwardrolling by an amount equal to an integral number of pitches, and meansfor interrupting the normal operation of the 40 tool holder in relationto the blank-carrier at the end of each forward rolling movement and forstarting the said normal operation after the beginning of eachsucceeding forward rolling movement.

32. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder reciprocating in a fixed path and adaptedto hold a cutter "of the rack type,

' two controlling mechanisms acting successively and alternately, onemechanism serving to simultaneously turn the carrier forward and to moveit rectilinearly forward whereby a forward rolling movement is effectedand the other mechanismserving to turn 65 the carrier backward and tomove it rectilinearly backward, the backward rectilinear movementexceeding that necessary for backward rolling by an amount equal to anintegral number of pitches,' and means for stopping the reciprocation ofthe tool holder after each forward rolling movement and for starting thesaid reciprocation after each backward rectilinear movement.

An automatic gear cutting machine comprising in combination, ablank-carrier,

a tool holder reciprocating in a fixed path and adapted to hold a cutterof the rack type, two controlling mechanisms acting successively andalternately, one mechanism serving to simultaneously turn the carrierforward and to move it rectilinearly forward whereby a forward rollingmovement is effected and the other mechanism serving to roll the carrierbackward and to move it rectilinearly backward Without rolling by anamount equal to an integral number of pitches, and means forinterrupting the normal operation of the tool holder in relation to theblank-carrier at the end of each forward rolling movement and forstarting the said normal operation after the beginning of eachsucceeding forward rolling movement.

34. An automatic gear'cutting machine comprising in combination, ablank-carrier, a tool holder reciprocating in a fixed path and adaptedto hold a cutter of the rack type, a reversible operating means servingto simultaneously turn the carrier forward and to move it rectilinearlyforward whereby a forward rolling movement is effected and to reversethe said movements --whereby backward rolling is effected, means forinterrupting the backward turning but not the backward rectilinearmovement by an amount equal to an integral number of pitches, and meansfor interrupting the normal operation of the tool holder in relation tothe blank carrier at the end of each forward rolling movement and forstarting the said normal operation after the beginning of eachsucceeding forward rolling movement.

35. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder reciprocating in a fixed path and adaptedto hold a cutter of the rack type,

two controlling mechanisms acting successively and alternately, onemechanism serving to simultaneously turn the carrier forward and to moveit rectilinearly forward whereby a forward rolling movement is effectedand the other mechanism serving to roll the carrier backward and to moveit rectilinearly backward without rolling by an amount equal to anintegral number of pitches, the said backward rolling being effectedboth before and after the said backward rectilinear movement, and meansfor interrupting the normal operation of the tool holder in relation tothe blank'carrier at the end of each forward rolling movement and forstarting the said normal operation after the beginning of eachsucceeding forward rolling movement.

36. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder reciprmrating in a fixed path and adaptedto hold a cutter of the rack type,

a reversible operating means serving to simultaneously turn the carrierforward and to move it rectilinearly forward whereby a 30 forwardrolling movement is effected and to reverse thesaid movements wherebybackward rolling is effected, means for interrupting the backwardturning but not the backward rectilinear movement by an amount equal toan integral number of pitches, the last said means acting after thebeginning and before the end of the said backward rolling movement, andmeans for interrupting the normal operation of the tool holder inrelation to the blank-carrier at the end of each forward rollingmovement and for starting the said normal operation after the beginningof each succeeding forward rolling movement.

37. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder reciprocating in a fixed path and adaptedto hold a cutter of the rack type, two controlling mechanisms actingsuccessively and alternately, one .mechanism serving to simultaneouslyturn the carrier forward and to move it rectilinearly forward whereby aforward rolling movement is effected and the other mechanism serving toturn the carrier backward and to move it rectilinearly backward atincreased speed, the backward rectilinear movement exceeding thatnecessary for backward rolling by an amount equal to an integral numberof pitches, and means for interrupting the normal operation of the toolholder in relation to the blank-carrier at the end of each forwardrolling movement and for starting the said normal operation after thebeginning of each succeeding forward rolling movement.

38. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder reciprocating in a fixed path and adaptedto hold a cutter of the rack type, two controlling mechanisms actingsuccessively and alternately, one mechanism serving to simultaneouslyturn the carrier forward and to move it rectilinearly forward whereby aforward rolling movement is effected and the other mechanism serving toturn the carrier backward and to move it rectilinearly backward atincreased speed, the backward rectilinear movement exceeding thatnecessary for backward rolling by an amount. equal to an integral numberofpitches, means for interrupting the normal operation of the toolholder in relation to the blank-carrier at the end of each forwardrolling movement and for starting the said normal operation after thebeginning of each succeeding forward rolling movement, and means forcausing the initial part of the forward rolling movement to take placeat increased speed.

39. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder normally reciprocating in afixed path andadapted to hold a cutter of the rack type, two threaded element-sadapt-- ed respectively for turning and rectilinearly moving theblank-carrier to effect rolling, and means associated with one of theaforesaid elements and tending to drive the carrierat an increasedspeed, the said element thus acting as a retarding device.

40. An automatic gear cutting machine comprising in combination, ablank-carrier,

.a tool holder normally reciprocating in a fixed path and adapted tohold a cutter of the rack type, two threaded elements adaptedrespectively for turning and rectilinearly moving the blank carrier toeffect rolling,

and a suplemental threaded element associated with one of the aforesaidelements for taking up play.

41. An automatic gear cutting machine comprising in combination, a blankcarrier, a tool holder normally reciprocating in a fixed path andadapted to hold a cutter of the rack type, two threaded elements adaptedrespectively for turning and rectilinearly moving the blank carrier toeffect rolling, a supplemental threaded element associated with one ofthe aforesaid elements and tending to drive the carrier at an increasedspeed to take up play, and non-positive means for rotating thesupplemental threaded element.

d2. An automatic gear cutting machine comprising in combination, ablank-carrier,

a tool holder normally reciprocating in a fixed path and adapted to holda cutter of the rack type, means for rolling the, carrier forward withrespect to the tool holder to effeet the generation of gear teeth on theblank. means for moving the carrier rectilinearly backward through adistance equal to an inte ral number of pitches, two movable control ingdevices, one operating in timed relation to the blank movements and theother operating in timed relation to the tool holder reciprocat-ions,and means jointly controlled by the two devicesfor stopping the toolholder at the end of the forward rolling of the blank-carrier and at theend of a reciprocation with the tool disengaged from the blank.

43. An automatic gear cutting machine comprising in combination, ablank-carrier,

a tool holder normally reciprocating in a fixed path and adapted to holda cutter of the forward rolling movement, and subsequently acting meansjointly controlled by the two controlling devices for stopping the toolholder at the end of a reciprocation with the tool disengaged from theblank.

44. An automatic gear cutting machine comprising in combination, ablank-carrier, a tool holder normally reciprocating in a fixed path andadapted to hold a cutter of the rack type, a head in which the toolholder reciprocates, the head being angularly adjustable to change theangle of the path of reciprocation, means for rolling the carrierforward with respect to the'tool holder to efli'ect the generation ofgear teeth on the blank, means for moving the carrier rectilinearlybackward through a distance equal to an integral number of pitches, twomovable controlling devices, one operating in timed relation to theblank movements and the other operating in timed relation to thesignature.

MAX MAAG.

